On Wed, Jul 25, 2007 at 06:14:20AM +0300, Avi Kivity wrote: > Aurelien Jarno wrote: > > On Fri, Jul 20, 2007 at 09:57:55AM +0300, Avi Kivity wrote: > > > >> Avi Kivity wrote: > >> > >>>> Please tell me what I can do to help debugging this problem. > >>>> Alternatively I have uploaded an image to reproduce the problem here: > >>>> http://temp.aurel32.net/kfreebsd-amd64.img.g > >>>> > >>>> > >>> I've downloaded the image and booted it three times using kvm HEAD. > >>> Each time I got to the login prompt. > >>> > >>> Is this always reproducible? Can you check with kvm HEAD (not that I > >>> think of anything that could have fixed this). > >>> > >>> > >>> > >> Sorry, that was on Intel. It reproduces easily on AMD. > >> > > > > By comparing the cases were the old and the new condition are different, > > I have found that the problem occurs for the lmsw and smsw instructions. > > > > Ah, I was looking at amd-specific instructions (vmx decodes lmsw) but > missed these two. Good work. > > > The patch below is very ugly, but it workarounds the problem. > > > > It's not ugly, it just lives in an ugly function. But it does lack a > changelog and a signoff. >
After a short discussion on IRC, it seems that all 0x02 0x01 instructions do not use the writeback. Please find an updated and signedoff patch below. KVM: disable writeback for 0x02 0x01 instructions. 0x02 0x01 instructions (ie lgdt, lidt, smsw, lmsw and invlpg) does not use writeback. This patch set no_wb=1 when emulating those instructions. Signed-off-by: Aurelien Jarno <[EMAIL PROTECTED]> diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c index 21ce977..cbbb9c5 100644 --- a/drivers/kvm/x86_emulate.c +++ b/drivers/kvm/x86_emulate.c @@ -1183,6 +1183,8 @@ pop_instruction: twobyte_insn: switch (b) { case 0x01: /* lgdt, lidt, lmsw */ + /* Disable writeback. */ + no_wb = 1; switch (modrm_reg) { u16 size; unsigned long address; -- .''`. Aurelien Jarno | GPG: 1024D/F1BCDB73 : :' : Debian developer | Electrical Engineer `. `' [EMAIL PROTECTED] | [EMAIL PROTECTED] `- people.debian.org/~aurel32 | www.aurel32.net ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel